The Fourth of July is America’s day off, a time to swim in the pool, grill hot dogs and hamburgers, and watch a parade and fireworks.

But for some the Fourth is the busiest day of all.

The Banner spoke to the people who make Independence Day work, whether at the pool or an urgent care center. We looked behind the scenes of the Inner Harbor’s fireworks display and Reisterstown’s favorite frozen dessert.

What is going through that lifeguard’s head?

By 10 a.m., lifeguards at the Jewish Community Center of Greater Baltimore in Owings Mills are geared up for the busiest day of the year. With sunglasses, sunscreen, rescue tube, whistle and oxygen mask in hand, 32 guards are on alert across the J’s four pools.

Teagan Stephenson, a veteran guard and swim teacher, says the high volume of people makes it harder to keep an eye on the pool.

From the guard chair, the pool resembles a jumble of bodies splashing and tumbling — “we’re on such high alert that sometimes we will jump into the pool to help a kid who doesn’t completely need it, but we’d rather be safe than sorry for a rescue,” Stephenson said.

The most common word of the day is “walk!” Stephenson finds himself and his crew yelling the word at kids excited by the pop music vibrating from a DJ, kids immersed in playing tag, Monkey in the Middle and Marco Polo.

Stephenson said they even have a guard stationed at the first-aid kit, treating pool toe and minor scrapes throughout the day.

Stephenson said he’ll drink over six bottles of water, eat many fruit popsicles from the staff freezer and wade in the pool to stay cool and attentive.

But guards also join the fun. A few years back, Stepheson spray-painted a massive American flag on the hill overlooking the J’s large family pool, rock wall and splash pad. Staff members tie-dye their shirts in patriotic colors, don temporary tattoos and take small American flags with them to their posts.

With more than 300 people visiting a day, the pool at closing needs to be shocked with chemicals and chlorine to neutralize all of the skin, germs and sunscreen. After closing time at sunset, guards often head to Baltimore’s fireworks shows.

The other things your physician at the urgent care has seen today

The Bayview location of Patient First Urgent Care is one of the busiest on the East Coast. Dr. Michele Henley says that, inevitably, by 8 a.m., a line will have formed outside the door with patients ill with the flu, strep throat or another virus.

The afternoon is when Henley’s office will likely begin to fill up with Fourth of July-themed injuries.

Forearms are scorched from pulling pies out of the oven in haste. Patients come in dehydrated, needing IVs. “Inevitably someone says that a knife slipped while they were rushing and cutting food, and they didn’t realize that they were cutting their finger,” Henley said.

The end of the night brings in the fireworks-related injuries — a kid who held on to one too long and has small burns or numbness in their fingers.

Some years ago, a man showed up on the holiday with a tick in his scrotum. Another year, an older woman got her hearing aid mixed up with her mac and cheese and ate it.

Otherwise, “the Fourth of July is pretty cut and dry,” Henley said.

When emergencies inevitably arise, EMS responds

Michael Hoffman, EMS captain of Baltimore County Fire Department, begins the Fourth with ambulances and engines scrubbed and shining, greeting families at parades across the county.

“You see little kids hoisted up by their parents, and they’re so excited,” Hoffman said. “It feels good to be able to give back to the public in this way, to feel pride in why you got into this job.”

But often his crew will get pulled away from the fun.

“Bigger holidays can mean bigger emergencies,” Hoffman said.

His crew responds to the kinds of emergencies you’d expect when it’s hot, busy and lots of people are out: dehydration, heat exhaustion, alcohol poisoning. Most emergencies are not unlike other days (apart from the occasional fingers blown off).

Hoffman said many emergencies can be avoided when you make a plan: Have water available; separate the use of fireworks and alcohol.

“We’re an all-hazard fire department, so we respond to everything,” said Bureau Chief Travis Francis, from EMS and hazmat to technical rescue.

In the early morning firefighters could be responding to a house exploding, and late at night they could be responding to a fireworks malfunction. In 2001, at the Catonsville celebration, the Baltimore County Fire Department responded when the shells of the fireworks fell over and set off into the crowd. Francis said the department requires a fire marshal to be present at every fireworks display. They inspect the equipment before and after the show.

“We knew taking this job that we would not always be home for the holidays. We wish we could be celebrating with our families, but we know what this job requires of us,” Hoffman said. “We might be tired and hungry, and we will show up every time, but we are human too.”

The Cow’s owner dishes out why his Italian ice so good and where you should get it

As owner of The Cow, the locally adored Italian ice shop on Reisterstown’s Main Street, Mike Reiner has spent 20 years serving frozen dessert on the Fourth of July. He is no stranger to the long line in front of the truck he’s manned for nearly a decade at Carroll County’s July Fourth celebration.

“You see anxious adults tapping their foot, thinking about what they will get, people smiling at the word sprinkles,” said Reiner, adding, “sitting on the curb and eating ice cream is a part of the social scheme of summer.”

Many of The Cow’s Italian ice flavors — cookie butter, peanut butter, churro, skylight — originated from the community.

“People would ask me if something can be a flavor, and it turns out that nearly anything in the grocery store can be frozen,” he said.

If it can be frozen, it can be made into Italian ice. “Even Old Bay, but turns out it does not taste good,” Reiner said.

If you take an ice cube out into the rays of July’s sun, it’ll melt in seconds. The secret to The Cow’s thick helping of Italian ice, Reiner said, is chemistry. Sugar traps air in the mix to give the water its volume.

On Friday night, the inside of The Cow’s truck will likely be sweaty and busy. Reiner’s crew members wear shorts and T-shirts to move as efficiently as possible as they serve mango sorbet and vanilla custard with crushed heath bars, whipped cream and a cherry on top.

They are a machine that slows only once throughout the night: during the fireworks display.

How do fireworks actually work? The man who designed the Inner Harbor’s show will tell you

Zack Paul, the lead pyrotechnical designer for Image Engineering, began preparing for Friday night’s fireworks displays in March by filling out compliance paperwork and getting a sense of the city’s expectations for its scale and scope.

In April, Paul ordered over 1,000 fireworks, a mixture of chrysanthemums, peonies, dahlias, jellyfish, wind bells and willows — each named by how they light up the sky.

In May and June, Paul began to organize the show itself. Because fireworks are technically in the percussive family, Paul designs every millisecond of the show, often to the beat of a song. Smaller shells are the buildup to the moment for a larger shell as the crescendo and finale.

Everything comes together in the week leading up to the show. The Image Engineering crew is on a barge docked at a marina that on the Fourth will be towed underneath the Domino Sugar factory’s large neon sign, about 800 or so feet from the water’s edge.

Racks are built to hold steady the tubes where the fireworks shells will be loaded, a process that can take days.

On Thursday, the crew wired each individual shell with its own electronic match, which gets wired together in a specific order so that, at showtime, pressing one button will begin the show.

“It’s all timed out beforehand in the design phase, where an internal clock goes through each millisecond, telling each individual pin when to fire,” Paul said.

Listening to the show, you might notice the rhythm at the beginning translating loosely to “The Star-Spangled Banner,” and the end is timed to play “The 1812 Overture.”

Paul will be standing on the barge from where all the fireworks are launched — in a hard hat, closed toe shoes, a vest, flotation device, eye protection and gloves — stepping back with his chin held high to admire the sky ablaze with patriotism.